One gallon of paint typically covers up to 400 square feet with one coat, although actual coverage varies by the paint, surface, application method, and other factors. To estimate how many gallons of paint you need, calculate the square footage you’re painting, account for the number of coats, and divide that number by the coverage rate of your paint.
For example, if you have 800 square feet of paintable surface and plan to apply two coats, you need enough paint for 1,600 square feet of coverage. At 400 square feet per gallon, that would be approximately 4 gallons of paint.
How Many Square Feet Does a Gallon of Paint Cover?
Many interior paint gallons cover approximately 350 to 400 square feet, but always check the coverage listed for the specific paint you’re using.
At that rate, 5 gallons of paint would cover approximately 1,750 to 2,000 square feet with one coat, or about 875 to 1,000 square feet with two coats.
Keep in mind that rough, textured, or porous surfaces may require more paint than smooth, previously painted surfaces.
How to Calculate How Many Gallons of Paint You Need
For a basic estimate, use this formula:
Paintable Square Footage of Walls × Number of Coats ÷ Coverage per Gallon = Gallons of paint needed
To calculate the paintable square footage of walls:
Add together the lengths of all four walls to get the perimeter. Then, multiply the perimeter by the height of the walls.
Perimeter × Height of Walls = Paintable Square Footage
For example, below is how you would calculate the paintable square footage for a 12 × 10 ft. room with 8 ft ceilings:
(12 + 12 + 10 + 10) × 8 = 352 square feet of wall area
You can then subtract the area occupied by doors and windows for a more precise estimate.
If that room requires two coats, you would need to cover roughly 704 square feet before accounting for doors and windows. With paint rated for 350 to 400 square feet per gallon, 2 gallons would generally be appropriate.
How Many Gallons of Paint Do You Need for a Room?
The amount of paint needed for a room depends on its dimensions, ceiling height, doors and windows, and how many coats you’re applying.
Here are some quick estimates for rooms with 8-foot ceilings:
| Room Size | Approx. Wall Area | Paint Needed for 2 Coats |
|---|---|---|
| 10 × 10 ft. | 320 sq. ft. | About 2 gallons |
| 10 × 12 ft. | 352 sq. ft. | About 2 gallons |
| 12 × 12 ft. | 384 sq. ft. | About 2 gallons |
| 12 × 15 ft. | 432 sq. ft. | About 2–3 gallons |
These estimates are based on total wall area before subtracting doors and windows and assume approximately 350 to 400 square feet of coverage per gallon.
For a typical bedroom, 2 gallons is often enough for two coats on the walls, although larger bedrooms or rooms with high ceilings may require more. A small bathroom will generally require less paint because of its smaller size and the wall area occupied by the shower, tile, vanity, and other features.
How Many Gallons of Paint Do You Need to Paint a House?
You can’t accurately determine how much paint a house needs from its floor square footage alone. A 1,000-square-foot house does not have only 1,000 square feet of paintable wall surface.
The number and size of rooms, ceiling height, layout, doors and windows, number of coats, and whether you’re also painting ceilings and trim all affect how much paint you’ll need.
For larger interior projects, see our more detailed estimates for:
- How Much Paint Is Needed to Paint a 1,500 Square Foot Interior?
- How Much Paint Is Needed to Paint a 2,000 Square Foot Interior?
- How Much Paint Is Needed to Paint a 2,500 Square Foot Interior?
- How Many Gallons of Paint Do You Need for a House Exterior?
Exterior paint needs depend on the actual paintable surface area of the house rather than just its interior square footage. The size and height of the home, siding or exterior material, surface condition, number of coats, and architectural features can all affect the amount of paint required.
For the best estimate, calculate the exterior surface area and use the coverage rate provided for the specific exterior paint you’re using.
How Much Ceiling Paint Do You Need?
Calculating ceiling paint is relatively simple. Multiply the length of the room by its width to determine the ceiling’s square footage.
A 12 × 12-foot room, for example, has a 144-square-foot ceiling. Account for the number of coats you plan to apply and divide the total coverage needed by the coverage rate of your ceiling paint.
What Affects How Much Paint You Need?
Several factors can change the amount of paint required for a project:
- Number of coats
- Coverage rate of the paint
- Surface condition and porosity
- Wall texture
- Major color changes
- Application method
- Doors, windows, and other unpainted areas
- Extra paint needed for touch-ups
Use your calculations as an estimate and check the specifications for the particular paint you’re purchasing.
Come to Our Stores for Help Calculating How Much Paint You Need
Not sure how many gallons of paint to buy? Stop by Loconsolo Paints with your room measurements and project details. Our knowledgeable team can help you estimate how much Benjamin Moore paint you’ll need and choose the right products for the job.
Visit one of our NYC paint store locations for paint, primer, and everything else you need to get started.